Field of the Disclosure
The present disclosure relates to a high-frequency filter utilizing the resonant frequency and anti-resonant frequency of a resonator, a front-end circuit, and a communication apparatus.
Description of the Related Art
Various high-frequency filters have been devised. These high-frequency filters include a variable-frequency filter disclosed in, for example, Patent Document 1. A variable-frequency filter, which is a single high-frequency filter, can provide a plurality of filter characteristics (bandpass characteristics and attenuation characteristics) corresponding to different passbands.
The variable-frequency filter disclosed in Patent Document 1 includes a plurality of piezoelectric resonators and a switch. The variable-frequency filter disclosed in Patent Document 1 changes the combination of piezoelectric resonators by switching between connection modes of the switch. As a result, a plurality of different transmission characteristics (attenuation characteristics) are provided.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2009-207116